Jaw-opening accuracy is not affected by masseter muscle vibration in healthy men

There is a functional integration between the jaw and neck regions with head extension-flexion movements during jaw-opening/closing tasks. We recently reported that trigeminal nociceptive input by injection of hypertonic saline into the masseter muscle altered this integrated jaw-neck function during jaw-opening/closing tasks. Thus, in jaw-opening to a predefined position, the head-neck component increased during pain. Previous studies have indicated that muscle spindle stimulation by vibration of the masseter muscle may influence jaw movement amplitudes, but the possible effect on the integrated jaw-neck function is unknown. The aim of this study was to investigate the effect of masseter muscle vibration on jaw-head movements during a continuous jaw-opening/closing task to a target position. Sixteen healthy men performed two trials without vibration (Control) and two trials with bilateral masseter muscle vibration (Vibration). Movements of the mandible and the head were registered with a wireless three-dimensional optoelectronic recording system. Differences in jaw-opening and head movement amplitudes between Control and Vibration, as well as achievement of the predefined jaw-opening target position, were analysed with Wilcoxon's matched pairs test. No significant group effects from vibration were found for jaw or head movement amplitudes, or in the achievement of the target jaw-opening position. A covariation between the jaw and head movement amplitudes was observed. The results imply a high stability for the jaw motor system in a target jaw-opening task and that this task was achieved with the head-neck and jaw working as an integrated system

The Longitudinal Relationship between Jaw Catching/Locking and Pain

Orofacial pain and joint-related dysfunction can negatively affect daily jaw function. A common cause for limitations in jaw movements is joint-related dysfunction such as various forms of catching and locking. However, knowledge is limited regarding the development and natural course of joint-related jaw dysfunction and its relationship to the onset and course of orofacial pain. Therefore, the aim was to evaluate the incidence, prevalence, and gender differences in jaw catching/locking over time and in relation to orofacial pain in the general population. Data from 3 validated screening questions on orofacial pain and jaw catching/locking were collected from all routine dental checkups in the Public Dental Health Services in Västerbotten, Sweden, from 2010 to 2017. Logistic generalized estimating equation was used to account for repeated observations and Poisson regression for incidence analysis. In total, 180,308 individuals (aged 5–104 y) were screened in 525,707 dental checkups. In 2010, based on 37,647 individuals, the prevalence of self-reported catching/locking was higher in women than in men (3.2% vs. 1.5%; odds ratio, 2.11; 95% confidence interval [CI], 1.83–2.43), and this relationship and magnitude remained similar throughout the study period. The annual incidence rate was 1.1% in women and 0.5% in men. Women were at a higher risk than men for reporting both first onset (incidence rate ratio [IRR], 2.29; 95% CI, 2.11–2.49) and persistent (IRR, 2.31; 95% CI, 2.04–2.63) catching/locking. For the onset subcohort (n = 135,801), an independent onset of orofacial pain or jaw catching/locking exclusively was reported by 84.1%, whereas a concurrent onset was reported by 13.4%. Our findings of higher incidence, prevalence, and persistence in women than in men indicate that the gender differences seen for orofacial pain are evident also for jaw catching/locking. The findings also suggest independent onset of self-reported catching/locking and orofacial pain, which reinforces the pathophysiological differences between these conditions

Even mild catastrophic thinking is related to pain intensity in individuals with painful Temporomandibular Disorders

AIMS: Temporomandibular disorders (TMD) are often associated with psychological comorbidities. One such comorbidity is pain catastrophizing, i.e., exaggeration of negative consequences of a painful event. The aim was to investigate catastrophizing in individuals with painful TMD compared to controls and the association between catastrophizing and pain intensity, number of pain sites and functional limitations. METHODS: A community-based sample of 110 individuals (83 women; 20-69 yrs) with painful TMDs (myalgia/arthralgia as per Diagnostic Criteria for TMD), and 190 age- and gender-matched controls (119 women; 20-69 yrs) from the Public Dental services in Västerbotten, Sweden participated. Associations between catastrophizing and functional jaw limitations, respectively, and painful TMD were evaluated with ordinal regression. adjusted for the effect of gender and age. Associations (Spearman's correlation) of the Pain Catastrophizing Scale (PCS) with Jaw Functional Limitation Scale (JFLS-20), pain site number (whole body pain map), and characteristic pain intensity (CPI) and intergroup comparisons (Mann-Whitney U test) of these variables were also calculated. RESULTS: Levels of catastrophizing, were associated with TMD pain (OR 1.6, 95%CI 1.1-2.6). Among individuals with painful TMD, catastrophizing was correlated to pain intensity (r=0.458, p<0.01) and functional limitations (r=0.294-0.321, p≤0.002), but not to number of pain sites. CONCLUSION: Compared to controls, community-based individuals with painful TMD demonstrated higher levels of pain catastrophizing, and this catastrophizing was associated with increased pain intensity and jaw dysfunction. The relatively low scores of pain catastrophizing suggest that even mild catastrophic thinking is associated with pain perception and jaw function, and should be considered in patient management